JPS6333468B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording density control method when data is recorded by a thermal recording method, and particularly to a recording density control method for facsimile received data.

For example, in a facsimile receiving and recording apparatus using a thermal recording method, there is a drawback that the recording data transmission time corresponding to the main scanning line is not constant, and this causes uneven recording density in the sub-scanning direction. this is,
This is because recording data transmitted to a facsimile reception and recording device for high-speed reception and recording is generally run-length. When recording data is run-length, the period of the drive pulse applied to the thermal recording head is generally not constant, and when simultaneously recording complex patterns in the main scanning direction, it takes a considerable amount of time to transmit the recording data. In short, thermal recording is performed by applying a driving pulse to the thermal recording head after a considerable period of time has elapsed. That is, when thermally recording a complex pattern portion, the time interval between the drive pulses is long, and conversely, when the pattern is not complex, the time interval is short.

By the way, in the thermal recording method, a pattern corresponding to recording data is thermally recorded on thermal recording paper by selectively applying a driving pulse to each thermal recording element in a thermal recording head. If the time intervals of the drive pulses are not constant, the temperature generated by the heat-sensitive recording element during heat-sensitive recording will be uneven, resulting in uneven recording density in the sub-scanning direction.

In order to eliminate this recording density unevenness, conventionally, the time interval of the recording start signal for each main scanning line, that is,
Measure the time interval of drive pulses with a timer,
Although the drive pulses are controlled according to the measured time interval, there is a drawback that the control circuit becomes unnecessarily complicated.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a method that can easily eliminate recording density unevenness in the sub-scanning direction without complicating a control circuit.

For this purpose, the present invention calculates the transmission time corresponding to each main scanning line by counting the number of codes of received data, and determines the pulse width of the drive pulse and the current according to this transmission time. At least one of the voltage value and the voltage value is controlled. Since the received data is synchronized with a clock pulse of a certain period, if the number of codes of the received data is calculated for each main scanning line, it is possible to determine the number of codes of the recorded data, although there is an error within the range of delay time variation due to data processing. The time required for transmission can be known, and if the number of codes of the received data can be determined using an existing data processing counter, the drive pulse can be easily generated without complicating the control circuit configuration. It can be controlled to

The present invention will be explained below with reference to FIGS. 1 and 2.

First, FIG. 1 shows an overview of received data recording control when controlling the pulse width of the drive pulse. As shown in the figure, the modulated received data from the facsimile transmitting side undergoes appropriate processing such as demodulation, and then the number of codes of that data is determined as received data in a counter unit 1, while a decoding unit 2 generates a decoding table. It is now converted to the original facsimile image signal. The original image signal thus obtained is applied to the thermal recording head, which is the thermal recording section 4, via the recording control section 3, and is made to function as a thermal recording element selection signal. If the recording control unit 3 issues a drive pulse generation command to the drive pulse generation/pulse width control unit 5 in this state, the generated drive pulses are simultaneously applied only to the selected thermal recording elements, and the main Thermal recording for a scanning line is intended to be terminated at one time.

Therefore, in general, it is sufficient to repeatedly perform the above control on the recording data corresponding to the main scanning lines that are sequentially transmitted from the facsimile transmitting side, but as can be seen from the above, when the recording data is In the case of length recording, the time from the start of receiving recording data to the generation of a drive pulse is generally not constant, and it is clear that the longer the time, the lower the temperature of the thermosensitive recording element. Therefore, if we compensate for the temperature drop in some way,
This means that uneven recording density in the sub-scanning direction can be prevented.

In this example, unevenness in recording density is prevented by controlling the time period during which current is applied to the heat-sensitive recording element. That is, if the pulse width of the drive pulse is not constant and is increased as the recording data transmission time is longer, the temperature drop in the heat-sensitive element caused by the recording data transmission time can be compensated for. Therefore, generally speaking, the pulse width of the drive pulse corresponding to the minimum recording data transmission time may be controlled in the direction of increasing the pulse width. The above-mentioned counter section 1 was originally provided for decoding processing, but it counts the number of codes of received data, and further calculates the recording data transmission time corresponding to the number of codes and calculates the pulse width of the drive pulse. If controlled, recording density unevenness can be eliminated without requiring a complicated control circuit.

Now, another example of the present invention will be explained with reference to FIG.
In this example, instead of controlling the pulse width of the drive pulse, the drive pulse generation/pulse voltage control section 6 controls the pulse voltage in the direction of increasing the pulse voltage value of the drive pulse corresponding to the minimum recording data transmission time. Except for the control, the situation is similar to the previous example. A similar effect can be obtained by controlling the pulse voltage and therefore the pulse current. Therefore, in general, it is sufficient to control at least one of the pulse width, pulse voltage, and pulse current of the drive pulse. In addition,
The present invention is applicable not only to the case where print data is converted into run lengths but also generally to cases where the print data transmission time corresponding to the main scanning line changes.

As explained above, the present invention calculates the recording data transmission time corresponding to the main scanning line from the number of codes of the recording data, and determines the pulse width, pulse voltage, and pulse voltage of the driving pulse given to the thermal recording head according to this recording data transmission time. At least one of the pulse currents is controlled. Since the number of recorded data can be determined using existing counter means, the present invention has the advantage of simplifying control and eliminating uneven recording density in the sub-scanning direction.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams each showing a schematic configuration of a received data recording control circuit in a facsimile receiving and recording apparatus according to the present invention. DESCRIPTION OF SYMBOLS 1... Counter section, 2... Decoding section, 3... Recording control section, 4... Heat sensitive recording section, 5... Drive pulse generation/pulse width control section, 6... Drive pulse generation/
Pulse voltage control section.

Claims (1)

[Claims] 1. Thermal recording is performed by selectively applying driving pulses to individual elements of a plurality of thermal recording elements arranged in a row in the main scanning line direction based on recording data corresponding to main scanning lines whose transmission time is not constant. In the thermal recording method, the time required to transmit the data is determined by counting the number of codes in the received pre-decoded recording data corresponding to the main scanning line, and the pulse of the drive pulse is A thermosensitive recording density control method characterized by controlling the magnitude of at least one of width, pulse voltage, and pulse current.